考點:小數(shù)四則混合運算,運算定律與簡便運算
專題:運算順序及法則,運算定律及簡算
分析:(1)先算加法,再算除法,最后算乘法;
(2)先算減法,再算乘法,最后算除法;
(3)先除以8,再乘8,然后再根據(jù)除法的性質進行簡算;
(4)先算小括號里面的除法,再算括號外面的除法;
(5)先算除法,再算減法;
(6)根據(jù)除法的性質進行簡算;
(7)先算減法,再按照從左向右的順序進行計算;
(8)先算小括號里面的除法,再算減法,最后算括號外面的除法;
(9)根據(jù)除法的性質進行簡算;
(10)先算乘法,再算除法,最后算減法;
(11)根據(jù)除法的性質進行簡算;
(12)根據(jù)乘法分配律進行簡算;
(13)先算除法,再算減法;
(14)按照從左向右的順序進行計算;
(15)先算加法,再算除法,最后算乘法;
(16)先算減法,再算除法,最后算加法;
(17)按照從左向右的順序進行計算;
(18)先算減法,再算乘法,最后算除法;
(19)先算小括號里面的除法,再算括號外面的除法;
(20)先算除法,再算減法;
(21)按照從左向右的順序進行計算;
(22)先算除法,再算乘法;
(23)先算減法,再算乘法,最后算除法.
解答:
解:(1)16.2÷(48.6+5.4)×0.5
=16.2÷54×0.5
=0.3×0.5
=0.15;
(2)0.36÷[(6.1-4.6)×0.8]
=0.36÷[1.5×0.8]
=0.36÷1.2
=0.3;
(3)4.9÷0.125
=4.9÷0.125÷8×8
=4.9÷(0.125×8)×8
=4.9÷1×8
=4.9×8
=39.2;
(4)2.38÷(59.5÷0.25)
=2.38÷238
=0.01;
(5)37.6-1.5÷0.24
=37.6-6.25
=31.35;
(6)9.9÷0.5÷2.2
=9.9÷(0.5×2.2)
=9.9÷1.1
=9;
(7)21.6÷(8.32-3.32)÷0.12
=21.6÷5÷0.12
=4.32÷0.12
=36;
(8)9.28÷(1-1.7÷2.5)
=9.28÷(1-0.68)
=9.28÷0.32
=29;
(9)3.6÷0.18÷20
=3.6÷(0.18×20)
=3.6÷3.6
=1;
(10)5.6×7.8-7.8÷(1.5×1.3)
=43.68-7.8÷1.95
=43.68-4
=39.68;
(11)0.8÷0.32
=0.8÷(0.8×0.4)
=0.8÷0.8÷0.4
=1÷0.4
=2.5;
(12)0.29×5.4+4.6×0.29
=0.29×(5.4+4.6)
=0.29×10
=2.9;
(13)3.48÷1.45-0.58÷1.45
=2.4-0.4
=2;
(14)2.24×16.5÷0.6
=36.96÷0.6
=61.6;
(15)16.2÷(48.6+5.4)×0.5
=16.2÷54×0.5
=0.3×0.5
=0.15;
(16)(74.8-20.2)÷91+0.4
=54.6÷91+0.4
=0.6+0.4
=1;
(17)0.175÷0.25×4
=0.7×4
=2.8;
(18)0.36÷[(6.1-4.6)×0.8]
=0.36÷[1.5×0.8]
=0.36÷1.2
=0.3;
(19)2.38÷(59.5÷0.25)
=2.38÷238
=0.01;
(20)37.6-1.5÷0.24
=37.6-6.25
=31.35;
(21)9.1÷0.13÷2.5
=70÷2.5
=28;
(22)0.4×(0.84÷3.36)
=0.4×0.25
=0.1;
(23)7.44÷[(54.7-17.5)×0.5]
=7.44÷[37.2×0.5]
=7.44÷18.6
=0.4.
點評:考查了運算定律與簡便運算,四則混合運算.注意運算順序和運算法則,靈活運用所學的運算定律簡便計算.